A new report says that the Environmental Protection Agency's current standards for naturally occurring fluoride levels in drinking water -- no more than 4 milligrams per liter of water -- are too high and put people at risk for the adverse health effects caused by excess fluoride.
The report was issued by the National Academies' National Research Council, a nonprofit institution that provides science and health policy advice to the federal government.
The NRC committee concluded unanimously that children exposed to the current maximum fluoride concentration are at risk for developing severe tooth enamel fluorosis, a permanent condition characterized by discoloration, enamel loss and pitting of the teeth. The committee also concluded that cumulative exposure to that level of fluoride can weaken bone and increase the risk of fracture in adults.
The NRC report states that in communities with water fluoride concentrations near 4 milligrams per liter, about 10 percent of children develop severe enamel fluorosis. The rate of severe fluorosis drops to almost zero in communities where the fluoride concentration is 2 milligrams per liter.
According to the committee's report, most of the drinking water in the country has a fluoride level much lower than the EPA's recommended cutoff point. But it's estimated that excessive fluoride levels affect about 200,000 people whose water has fluoride levels of 4 mg/L or higher, and an additional 1.4 million people whose water has 2 mg/L of fluoride, which can lead to such cosmetic side effects as tooth discoloration.
"The report in no way examines or calls into question the safety of community water fluoridation, which is the process of adding fluoride to public water supplies to reach an optimal level of 0.7 to 1.2 milligrams per liter in order to protect people against tooth decay," according to a recent statement from the American Dental Association.
Rather, the research council says the EPA needs to lower its current maximum contaminant level to ensure that optimal fluoride levels are met.
In some areas of the U.S., natural runoff from fluoride-containing rocks can end up in public water systems. South Carolina, Texas, Oklahoma, and Virginia have the largest populations receiving water supplies with greater than 4mg/L of fluoride. Less populated areas with high fluoride levels include Idaho, New Mexico, and Colorado.
"We aren't telling the EPA what the new standard ought to be, but we're recommending that they do the risk assessment ... to set a new level," said Charles Poole, a professor of epidemiology at University of North Carolina and a member of the council's committee.
Dale Kemery, a press officer at the EPA, agrees.
"The agency does have regulatory responsibility over fluoride and will give serious consideration to the NRC's recommendations," Kemery said.
When asked when the changes might take place, Kemery said, "I have no idea at this point because the report is quite new and quite thick -- 400 pages."
Is Tap Water Safe?
Much stricter fluoride standards are recommended by the Environmental Working Group, a nonprofit environmental research organization based in Washington, D.C. It believes that "fluoride exposure should be limited to toothpaste, where it provides the greatest dental benefit and presents the lowest overall health risk."
Environmental Working Group's major concern is infants who are bottle fed with formula reconstituted with tap water.
"In Boston, for example, more than 60 percent of the exclusively formula-fed babies exceed the safe dose of fluoride on any given day," the group said in a recent press release.
This is based on fluoride data compiled from municipal drinking water systems from 1998 to 2002 that showed that, of the 28 largest cities in the United States, Boston had the highest fluoride level -- 1.30 milligrams per liter -- exceeding the recommended range of 0.7-1.2 milligrams per liter.
So is it safe for infants to drink formula reconstituted with tap water?
"Yes, I think that's safe, quite frankly, because that's what infants have been doing across this country for many decades," said Dr. John Stamm, a professor at the University of North Carolina School of Dentistry and spokesman for the ADA. "The public health safety data has been accumulating, and none of those infants have developed moderate or severe fluorosis, which is the criterion that the NRC report is using to evaluate the safety of fluoride."
Ask Your Municipality About Water Supply
But that doesn't mean people shouldn't be cautious, he said.
"All consumers should be aware of the fluoride level in their drinking water," Stamm said. "This is a matter of personal health interest. If you live in a fluoridated community, that information is available from a telephone call to the water company. If you live in a rural community, you may not know how much fluoride is in your well water; it then behooves you to ask your dentist to refer you to the state agency that can determine your fluoride concentration."
Experts said that switching from tap water to bottled water is probably an unnecessary step because bottled water usually has too little fluoride to protect against cavities, although there is wide variability among brands and most do not state how much fluoride they contain.
"Bottled water has to meet the same drinking water standards as tap water," Kemery said.
And for people who are considering home filtering systems, look carefully at their specifications, too.
"Home filtering systems vary widely in their ability to filter out fluoride, from 15 to 90 percent," said Poole.
What can parents do to protect their kids? The most important thing is to teach them not to swallow their toothpaste, Stamm said.
"Toothpaste is designed to have a lot of fluoride -- 1,000 milligrams per liter. Young children should use only a pea-size quantity of toothpaste when they brush," Stamm said.